Method and apparatus for spatial sharing in wireless local area network (wlan) systems

ABSTRACT

To facilitate spatial sharing, signaling may be used. A first node may receive one or more frame exchanges between a second node and a third node, wherein the second node is associate with the third node. The first node may then detect a spatial sharing scenario (SSS) with an overlapping basic service set (BSS) based on the received one or more frame exchanges. Also, the first node may transmit a directional poll request to at least a fourth node associated with the first node based on the detected SSS, and thereby null directional transmissions associated with the second node, the third node or both. The first node may then receive a direction poll response from the fourth node. Further, the first node may transmit one or more directional, beamformed transmissions to the fourth node simultaneously with directional, beamformed transmissions by the second node to the third node.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage, under 35 U.S.C. §371, ofInternational Application No. PCT/US2015/049744 filed Sep. 11, 2015,which claims the benefit of U.S. Provisional Application No. 62/049,357filed Sep. 11, 2014 and U.S. Provisional Application Ser. No. 62/073,689filed Oct. 31, 2014, the contents of which are hereby incorporated byreference herein.

SUMMARY

To facilitate spatial sharing or reuse, signaling may be used in awireless local area network (WLAN) system. A first node may receive oneor more frame exchanges between a second node and a third node, whereinthe second node is associate with the third node. The first node maythen detect a spatial sharing scenario (SSS) with an overlapping basicservice set (BSS) based on the received one or more frame exchanges.Also, the first node may transmit a directional poll request to at leasta fourth node associated with the first node based on the detected SSS,and thereby null directional transmissions associated with the secondnode, the third node or both. The first node may then receive adirection poll response from the fourth node. Further, the first nodemay transmit one or more directional, beamformed transmissions to thefourth node simultaneously with directional, beamformed transmissions bythe second node to the third node.

Also, a station (STA) may receive a wireless signal including a preambleof a packet. An energy level of the signal received may exceed a clearchannel assessment (CCA) threshold. The STA may determine, using acarrier sense multiple access (CSMA) protocol, to ignore a payloadportion of the packet based on information contained in the preamble andadjust the CCA threshold to account for the payload portion of thepacket. The STA may then conduct CSMA wireless medium access during thepayload portion of the packet using the adjusted CCA threshold. In anexample, the STA may receive the preamble of the packet via a beamformedsignal. In another example, the STA may receive the preamble of thepacket via an omni-directional signal.

Further, signaling may be used for procedures of directionaltransmission from a first transmitter to a first receiver. If the firsttransmitter and first receiver want to allow their directional transmitopportunity (TXOP) to be spatially shared by other nodes, they may havean omni-directional spatial sharing frames exchange preceding theirdirectional TXOP. The omni frames preceding the directional TXOP willindicate that the subsequent TXOP (and data frames with the TXOP) willbe directional transmission.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the following description,given by way of example in conjunction with the accompanying drawingswherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 is an diagram of an example of a Spatially Orthogonal (SO)Condition;

FIG. 3 is a diagram of another example of an SO Condition.

FIG. 4 is a diagram of a further example of an SO Condition;

FIG. 5 is a diagram of an additional example of an SO Condition;

FIG. 6 is a diagram of an example of using clear to send (CTS)-to-selfto facilitate the detection of the SO conditions;

FIG. 7 is a diagram of an example of medium access when a station (STA)decides to drop a packet based on the received preamble or otherindicators;

FIG. 8 is a diagram of example procedures of a spatial sharing exchangewith multicast/broadcast transmission;

FIG. 9 is a diagram of an example of spatial sharing;

FIG. 10 is a diagram of another example of spatial sharing;

FIG. 11 is a diagram of an example of signaling in a spatial sharingscenario (SSS);

FIG. 12 is a diagram of a further example of spatial sharing;

FIG. 13 is a diagram of an additional example of spatial sharing;

FIG. 14 is a diagram of yet another example of spatial sharing; and

FIG. 15 is a diagram of an example of a method of continued back-off.

DETAILED DESCRIPTION

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the other networks 112. By way of example, the base stations 114a, 114 b may be a base transceiver station (BTS), a Node-B, an eNode B,a Home Node B, a Home eNode B, a site controller, an access point (AP),a wireless router, and the like. While the base stations 114 a, 114 bare each depicted as a single element, it will be appreciated that thebase stations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, i.e., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple-output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRA), whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (i.e.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internet protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, i.e., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 130 and/or the removable memory 132.The non-removable memory 130 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b, 102c over the air interface 116. The RAN 104 may also be in communicationwith the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface.

The core network 106 shown in FIG. 1C may include a mobility managementgateway (MME) 142, a serving gateway 144, and a packet data network(PDN) gateway 146. While each of the foregoing elements are depicted aspart of the core network 106, it will be appreciated that any one ofthese elements may be owned and/or operated by an entity other than thecore network operator.

The MME 142 may be connected to each of the eNode-Bs 142 a, 142 b, 142 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices. An access router (AR) 150 of a WLAN 155 may be in communicationwith the Internet 110. The AR 150 may facilitate communications betweenAPs 160 a, 160 b, and 160 c. The APs 160 a, 160 b, and 160 c may be incommunication with STAs 170 a, 170 b, and 170 c.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

A WLAN in Infrastructure basic service set (BSS) mode has an AccessPoint (AP) for the BSS and one or more stations STAs associated with theAP. The AP typically has access or an interface to a distribution system(DS), or another type of wired/wireless network that carries trafficin/out of the BSS. Traffic to STAs that originates from outside the BSSarrives through the AP and is delivered to the STAs. Traffic originatingfrom STAs to destinations outside the BSS is sent to the AP to bedelivered to the respective destinations. Traffic between STAs withinthe BSS may also be sent through the AP, wherein the source STA sendstraffic to the AP and the AP delivers the traffic to the destinationSTA. Such traffic between STAs within a BSS is really peer-to-peertraffic. Such peer-to-peer traffic may also be sent directly between thesource and destination STAs with a direct link setup (DLS) using an IEEE802.11e DLS or an IEEE 802.11z tunneled DLS (TDLS). A WLAN inIndependent BSS mode has no AP and STAs communicate directly with eachother.

Sectorized transmission has been discussed in IEEE 802.11ad. Inunmodified IEEE 802.11ad, all STAs and APs are assumed to conductsectorized beam transmissions. A beamformed TXOP may be reserved bytransmitting beamformed request to send (RTS)/directional multi-gigabits(DMG) clear to send (CTS) frames. The STAs that receive the RTS/DMG CTSshall obey their network allocation vectors (NAVs). A recipient DMG STAwhich receives a valid RTS from the source STA during a Service Period(SP) may also transmit a DMG denial to send (DTS) to tell the source STAto postpone transmissions if one of the NAV timers at the recipient STAis non-zero.

A personal basic service set (PBSS) central point (PCP) may request apair of STAs that intend to conduct directional transmissions to eachother to conduct measurements while another pair of STAs is activelytransmitting directionally; subsequently, the PCP may request that thesecond pair of STAs to conduct directional measurements while the firstpair of STAs transmitting directionally to each other. If both pairs ofSTAs report no or little interference from each other's transmissions,the two pairs of STAs may be scheduled in the same Service Period (SP)to conduct concurrent directional transmissions.

New spectrum is being allocated in various countries around the worldfor wireless communication systems such as WLANs. Such spectrum is oftenquite limited in the size and also in the bandwidth of the channels theycomprise. In addition the spectrum may be fragmented in that availablechannels may not be adjacent and may not be combined for largerbandwidth transmissions. Such is the case, for example, in spectrumallocated below 1 gigahertz (GHz) in various countries. WLAN systems,for example, built on the IEEE 802.11 Standard, may be designed tooperate in such spectrum. Given the limitations of such spectrum, theWLAN systems will only be able to support smaller bandwidths and lowerdata rates compared to high throughput (HT)/very high throughput (VHT)WLAN systems, for example, based on the IEEE 802.11n/802.11ac Standards.

The IEEE 802.11ah Task Group (TG) has been established to developsolutions to support WiFi systems in the sub-1 GHz band. The IEEE802.11ah TG is targeting to achieve the following requirements:orthogonal frequency-division multiplexing (OFDM) physical (PHY) layeroperating below 1 GHz in license-exempt bands excluding television whitespace (TVWS); enhancements to medium access control (MAC) to supportPHY, coexistence with other systems (e.g. IEEE 802.15.4 and P802.15.4g);and optimization of rate vs. range performance (range up to 1 km(outdoor) and data rates >100 Kbit/s). The following use cases have beenadopted by the TG for IEEE 802.11ah: Use Case 1: Sensors and meters; UseCase 2: Backhaul Sensor and meter data and Use Case 3: Extended rangeWi-Fi for Cellular offloading.

The spectrum allocation in some countries is quite limited. For example,in China the 470-566 and 614-787 megahertz (MHz) bands only allow 1 MHzbandwidth. Therefore, there will be a need to support a 1 MHz onlyoption in addition to a support for a 2 MHz with 1 MHz mode also. Theunmodified IEEE 802.11ah PHY is required to support 1, 2, 4, 8, and 16MHz bandwidths.

The IEEE 802.11ah PHY operates below 1 GHz and is based on the IEEE802.11ac PHY. To accommodate the narrow bandwidths required by IEEE802.11ah, the IEEE 802.11ac PHY is down-clocked by a factor of 10. Whilesupport for 2, 4, 8, and 16 MHz can be achieved by the 1/10down-clocking described above, support for the 1 MHz bandwidth mayrequire a new PHY definition with an fast Fourier transform (FFT) sizeof 32.

In IEEE 802.11ah, a key use case defined is for meters and sensors, inwhich up to 6000 STAs should be supported within one single BSS. Thedevices such as smart meters and sensors have very differentrequirements pertaining to the supported uplink and downlink traffic.For example, sensors and meters could be configured to periodicallyupload their data to a server which will most likely be uplink trafficonly. Sensors and meters can also be queried or configured by theserver. When the server queries or configures a sensor or meter, it willexpect that the queried data should arrive within a setup interval.Similarly, the server/application will expect a confirmation for anyconfiguration performed within a certain interval. These types oftraffic patterns seem to be very different than the traditional trafficpatterns assumed for the WLAN systems.

In the IEEE 802.11ah signal (SIG) field of the physical layerconvergence procedure (PLCP) preamble of a packet, 2 bits are used toindicate the type of acknowledgment expected as a response (e.g., anearly acknowledgement (ACK) Indication) to the packet. The 2 bit ACKindication (00: ACK; 01: block acknowledgement (BA); 10: No ACK; 11: aframe that is not ACK, BA or CTS) is signaled in the SIG field.

The following views of sectorization operations have been discussed inIEEE 802.11ah. An IEEE 802.11ah AP may conduct sectorized transmissions,while an IEEE 802.11 non-AP may conduct omni-directional transmissions.

Sectorized Beam Operation may include Type 1 Sectorization. The AP inType 1 Sectorization may both transmit and receive using omni- andsectorized beams. Further, the AP may switch back and forth betweensectorized beam(s) and an omni-beam. Also, a sectorized beam may be usedwhen an AP is aware of the STA's best sector or in a scheduledtransmission such as a restricted access window (RAW) or during TXOP ofa STA. AP switch back to an omni-beam otherwise. In addition, asectorized transmit beam may be used in conjunction with the sectorizedreceive beam. Further, an AP may associate a STA with a specific group(e.g., same sector/group ID) based on the STA's best sector.

In an example of Sectorized Beam Operation, Four Spatially Orthogonal(SO) Conditions have been proposed for Type 1 Sectorized Operations.These SO Conditions may be referred to as SO Condition 1, SO Condition2, SO Condition 3 and SO Condition 4.

FIG. 2 is a diagram of an example of an SO Condition. The illustrationof example TXOP protection 200 may be referred to as SO Condition 1. Inan example, an AP 210 may use an omni frame to set up TXOP protectionfor a sectorized beam transmission 270. The omni-preamble may beincluded in an omni-packet 230 and included in the beginning of a longpacket (or long frame) 250. Once the proper TXOP protection is set upwith a long preamble, the sectorized transmission 270 (with greenfieldbeamforming (BF)) may be used for the remainder of the TXOP.

In an example, the SO condition may be confirmed by an overlapping BBS(OBSS) STA/AP (not shown) not receiving a transmission from STA 220 anda sectorized transmission from AP 210. For example, an OBSS STA may notreceive a transmission from STA 220 when the OBSS STA expects afollowing STA 220 transmission when it sees Ack Ind=00, 10, AckInd=11/Ack Policy=00 in the Omni packet 230 of the omni-preamble of AP210; and the OBSS STA may not receive from AP 210 a sectorizedtransmission portion within the long packet 250.

In a further example, STA 220 may transmit an ACK or response 240 afterthe AP transmits the omni packet 230. Also, the STA 220 may transmit anACK 260 after the AP transmits the long packet 250. The STA 220 may seta NAV 265 after the STA 220 begins to transmit the ACK 260.

Further, the AP 210 may set a NAV 235 when the AP 210 begins to transmitthe omni packet 230 and a NAV protected BF duration 255 after the AP 210begins to transmit the long packet 250. An OBSS STA and/or OBSS AP (notshown) may then spatially re-use a channel 245.

FIG. 3 is a diagram of another example of an SO Condition. Theillustration of example TXOP protection 300 may be referred to as SOCondition 2. In an example, an AP 310 can use a short-preamble withomni-transmission to set up TXOP protection for a sectorized beamtransmission 370. An omni-beam may include an omni-packet 330 and ashort packet 350. As shown in the examples herein, the TXOP protectionmay be set up at the second transmission by an AP. Once the proper TXOPprotection is set up, the sectorized transmission 370 (with greenfieldBF) may be used for the remainder of the TXOP.

In an example, the SO condition may be confirmed by an OBSS STA/AP (notshown) not receiving a transmission from STA 320 and a sectorizedtransmission from AP 310. For example, an OBSS STA may not receive atransmission from STA 320 when the OBSS STA expects a following STA 320transmission when it sees Ack Ind=00, 10, or Ack Ind=11/Ack Policy=00 inthe Omni packet 330 of the omni-beam of AP 310; and the OBSS STA may notreceive from AP 310 a sectorized transmission following the omni packet330 with ACK Policy=Block Ack*.

In a further example, STA 320 may transmit an ACK or response 340 afterthe AP 310 transmits the omni packet 330. Also, the STA 320 may transmitan ACK or response 360 after the AP transmits the short packet 350 andshort packet 352. The AP 310 may transmit with ACK Policy=BACK or NOACK*. The STA 320 may set a NAV 365 after the STA 320 begins to transmitthe ACK or response 360.

Further, the AP 310 may set a NAV 335 when the AP 310 begins to transmitthe omni packet 330 and a NAV 355 after the AP 310 begins to transmitthe short packet 350. An OBSS STA and/or OBSS AP (not shown) may thenspatially re-use a channel 345.

FIG. 4 is a diagram of a further example of an SO Condition. Theillustration of example TXOP protection 400 may be referred to as SOCondition 3. In an example, an AP 410 may start a frame exchange with anomni-RTS 430 to solicit a CTS response 440 from a STA 420 and then usethe omni-transmission to set up protection for the duration of asectorized beam transmission 457. An omni-preamble may include anomni-RTS 430 and a long omni-directional preamble 450. The AP 410 maythen switch to the sectorized beam transmission 457 for the remainder ofthe protected duration, which may be a NAV protected BF formation 455.The sectorized transmission 457 may be preceded by the longomni-directional preamble 450. The sectorized transmission 457 mayinclude a short preamble 452.

In a further example, STA 420 may transmit an ACK 460 after the AP 410transmits the long preamble 450. The STA 420 may set a NAV 465 after theSTA 420 begins to transmit the ACK 460.

Further, the AP 410 may set a NAV 435 when the AP 410 begins to transmitthe omni-RTS 430 and a NAV 455 after the AP 410 begins to transmit thelong omni-directional preamble 450. An OBSS STA and/or OBSS AP (notshown) may then spatially re-use a channel 445.

In another example, an AP 470 may start a frame exchange with anomni-RTS 471 to solicit a CTS response 481 from a STA 480 and then usethe omni-transmission to set up the protection for the duration of asectorized beam transmission 477. The AP 470 may then switch to thesectorized beam transmission 477 for the remainder of the protectedduration, which may be a NAV protected BF formation 474. The sectorizedtransmission 477 may be preceded by a short omni-directional preamble473. The sectorized transmission 477 may include a short packet 475.

In a further example, STA 480 may transmit an ACK 483 after the AP 470transmits the short omni-directional preamble 473. The STA 480 may set aNAV 485 after the STA 480 begins to transmit the ACK 483.

Further, the AP 470 may transmit with ACK Policy=BACK or NO ACK*. Also,the AP 470 may set a NAV 472 when the AP 470 begins to transmit theomni-RTS 471 and a NAV 474 after the AP 470 begins to transmit the shortomni-directional preamble 473. An OBSS STA and/or OBSS AP (not shown)may then spatially re-use a channel 487.

In an example, the SO condition may be confirmed by an OBSS STA or AP(not shown) which may observe the omni-transmission of AP 410 and/or AP470 but not the beamformed transmission of the APs and not thetransmissions of STA 420 and/or STA 480.

FIG. 5 is a diagram of an additional example of an SO Condition. Theillustration of example TXOP protection 500 may be referred to as SOCondition 4. In an example, the TXOP protection may be set up by omnitransmission for a duration within a TXOP and if the SO condition isconfirmed by an OBSS STA/AP, the OBSS STA/AP may cancel its NAV toinitiate a new SO exchange starting with a non-BF RTS/CTS. Once an APswitches to the sectorized beam transmission during an exchange, it maycontinue with greenfield sectorized beam transmission for the remainderof the protected duration. In examples disclosed herein, an SO conditionmay be defined as an OBSS STA/AP which receives the omni-transmissionbut not the sectorized transmission from the AP (which is either theTXOP holder or responder) and not the transmission from the STA (whichis either the TXOP responder or holder).

In an example, a STA 520 may start a frame exchange with aPS-Poll/Trigger/Other Frame 540. An AP 510 may then transmit anomni-preamble to set up protection for the duration of a sectorized beamtransmission 557. The omni-preamble may include a long packet (or longpreamble) 550. The AP 510 may transmit the long packet 550 in responseto the PS-Poll/Trigger/Other Frame 540. The AP 510 may switch to thesectorized beam transmission 557 for the remainder of the protectedduration. The sectorized transmission 557 may be preceded by the longpacket 550.

In a further example, STA 520 may transmit an ACK or response 560 afterthe AP 510 transmits the long packet 550. The STA 520 may set a NAV 565after the STA 520 begins to transmit the ACK 560.

Further, the AP 510 may set a NAV 555 when the AP 510 begins to transmitthe long packet 550. An OBSS STA and/or OBSS AP (not shown) may thenspatially re-use a channel 530. In an example, the OBSS STA and/or OBSSAP (not shown) may then spatially re-use the channel 530 on a conditionthat the AP transmission, such as the long packet 550, can be identifiedas the response to the PS-Poll/Trigger/Other Frame 540.

In another example, a STA 580 may start a frame exchange with aPS-Poll/Trigger/Other Frame 581. An AP 570 may then transmit anomni-preamble to set up protection for the duration of a sectorized beamtransmission 577. The omni-preamble may include a short packet (or shortpreamble) 571. The AP 510 may transmit the short packet 571 in responseto the PS-Poll/Trigger/Other Frame 581. The AP 570 may switch to thesectorized beam transmission 577 for the remainder of the protectedduration. The sectorized transmission 577 may be preceded by the shortpacket 550. The sectorized transmission 577 may include a short packet(or short preamble) 575.

In a further example, STA 580 may transmit an ACK or response 583 afterthe AP 570 transmits the short packet 571. The STA 580 may set a NAV565. In an example, the STA 580 may set the NAV 565 before the STA 580begins to transmit the ACK or response 583.

Further, the AP 470 may transmit with ACK Policy=BACK or NO ACK*. Also,the AP 570 may set a NAV 572 when the AP 570 begins to transmit theshort packet 572. An OBSS STA and/or OBSS AP (not shown) may thenspatially re-use a channel 587. In an example, the OBSS STA and/or OBSSAP (not shown) may then spatially re-use the channel 587 on a conditionthat the AP transmission, such as the short packet 572, can beidentified as the response to the PS-Poll/Trigger/Other Frame 581.

FIG. 6 is a diagram of an example of using CTS-to-self to facilitate thedetection of the SO conditions. In the illustration of example TXOPprotection 600, with respect to sectorized beam operation, informationelements may be used for Type 0 and Type 1 Sectorization. In an example,an AP 610 may transmit a CTS-to-self 630 as an omni-transmission withSO. The AP 610 may then transmit an omni-preamble 650 to set upprotection for the duration of a sectorized beam transmission 670. TheSTA 620 may receive the omni-preamble 650. The AP 610 may switch to thesectorized beam transmission 670 for the remainder of the protectedduration. In an example, the CTS-to-self 630 (which precedes SOconditions 1 or 2) may include a 1-bit sector ID indicator to facilitatethe detection of the SO conditions. Further, the AP 610 may set a NAV660 when the AP 610 begins the sectorized beam transmission 670.

In the current main stream unmodified WiFi standards (for example, IEEE802.11n, IEEE 802.11ac and the like), spatial sharing is not supported(and may not be allowed) in an OBSS. Within an OBSS, only one TXOP isallowed. IEEE 802.11ax has a requirement for supporting dense deploymentscenarios, higher area throughput, and substantially improved spectralefficiency. To support these requirements of IEEE 802.11ax, a moreefficient mechanism to utilize the channel medium is required. Further,with the dense deployment scenarios and higher requirements on areathroughputs and spectral efficiency in TGax, a more efficient mechanismto utilize the channel medium is required to achieve the goal.

Additionally, in the current unmodified IEEE 802.11ad standard,orthogonal beamforming between two pairs is allowed but only with ascheduled MAC. In the current unmodified IEEE 802.11ah standard,TXOP-based sectorization may be used to allow some spatialsharing/reuse, however it is limited to sectorization and supportsonly-AP initiated spatial reuse. The increased requirements for IEEE802.11ax may be addressed by a more flexible, and comprehensive,mechanism for spatial sharing. Further, with the dense deploymentscenarios, higher requirements on area throughputs and spectralefficiency, and diverse use cases (including peer to peercommunications) in IEEE 802.11ax, a more flexible and comprehensivemechanism of spatial sharing is desirable for IEEE 802.11ax.

FIG. 7 is a diagram of an example of medium access when a STA decides todrop a packet based on the received preamble or other indicators. Asshown in the illustration of the example of medium access 700, a problemmay occur when a STA may decide to ignore a packet that it is currentlyreceiving based on the information obtained from the preamble 710, andsubsequently conduct normal medium access procedures (with references tocolor and clear channel assessment (CCA)). MAC and PHY procedures areneeded to define MAC status transitions and to support correction mediumaccess and packet receptions when a STA decides to ignore a packet basedon the information currently received, such as information contained inthe preamble 710. In an example procedure, the MAC/CCA status may bebusy 750 during the preamble 710. A status 760, such as an idle status,may need to be determined during the frame body 720.

In order to facilitate more efficient spatial sharing or reuse in TGaxsystem, the following signaling procedures may be used. In the followingexamples, directional transmission from a first transmitter to a firstreceiver are described.

If the first transmitter and first receiver want to allow theirdirectional TXOP to be spatially shared by other nodes, they may have anomni-directional spatial sharing frames exchange preceding the operationusing a directional TXOP.

The frames transmitted using an omni transmission preceding thedirectional TXOP may indicate that the subsequent TXOP (and data frameswith the TXOP) will be a directional transmission. Also, as a protectionof the directional transmission procedure, frame(s) transmitted using anomni-transmission preceding the directional TXOP procedure may indicatewhether the directional TXOP procedure may be spatially shared by othernodes or not. The indication of an allowed subsequent directional TXOPand spatial sharing procedure for this TXOP may be implemented as anN-bit bitfield explicitly in any, or all, of the PLCP header, the MACheader or the framebody of the control and/or associated action frames.In another example, the indication of an allowed subsequent directionalTXOP and spatial sharing procedure for this TXOP may be indicated byother methods, such as cyclic redundancy code (CRC) masking, scramblerinitiation seeds values, a relative phase change in contiguous SIGfields or pilots (or pilot values and/or patterns), and/or signalpatterns in the PLCP header.

As used herein, an omni-preamble may be used to describe thetransmission of a preamble using an omni-transmission. Further, as usedherein, a directional-preamble may be used to describe the transmissionof a preamble using a directional transmission.

The omni-preamble and directional-preamble of the directional data framemay indicate that the rest of the data frames will be directionaltransmission. The first transmitter and first receiver may allow theirdirectional TXOP to be spatially shared by other nodes.

The indication of the allowance for spatial sharing may be indicated inthe directional frame, such as in the omni-preamble anddirectional-preamble of the directional frame, by setting aSpatialSharingAllow bit to 1. Such an indication may also imply that thepresence of an omni-frames exchange procedure prior to the commencementof directional-transmissions.

The indication that directional transmission is taking place for theremainder of the frame, and that directional transmission and spatialsharing is allowed for this TXOP may be implemented as an N-bit bitfieldexplicitly in the PLCP header. In another example, the indication of anallowed subsequent directional TXOP and spatial sharing procedure forthis TXOP may indicated by other methods, such as CRC masking, scramblerinitiation seeds values, a relative phase change in contiguous SIGfields or pilots (or pilot values and/or patterns) and/or signalpatterns in the PLCP header.

In order to protect the initial directional TXOP between the firsttransmitter and first receiver, the following example protectionmechanisms for spatial sharing may be used. In an example, another nodemay attempt to spatially share the directional TXOP between the firsttransmitter and first receiver only if it receives either at least oneomni-directional frame preceding the directional TXOP or theOmni-preamble in the directional frame(s) indicating spatial sharing isallowed, or at least one directional frame in the TXOP indicatingspatial sharing is allowed.

In further example, if another node attempts to spatially share thedirectional TXOP between the first transmitter and first receiver, itmay check the BSS Color in the PLCP preamble of the receivedomni-directional frame preceding the directional TXOP or the directionalframes in the TXOP. If the BSS Color is the same BSS and the directionalTXOP between the first transmitter and first receiver is between an APand a non-AP STA, then the node may attempt to spatially share thedirectional TXOP. In this case, the transmission may be limited topeer-to-peer STA communications.

In another example, the received power level, or the CCA level, at theother node that is attempting to enable spatial sharing may be ensuredto not exceed a threshold, which may be a pre-determined threshold. Thethreshold may be set statically in the standards or set semi-staticallyby the AP. Further, the value of the threshold may be differentdepending on the BSS color. For example, two different threshold valuesfor spatial sharing may be used for the cases where the BSS Color in thePLCP preamble of the received omni-directional frame preceding thedirectional TXOP or the directional frames in the TXOP is the same BSSvs. different BSS. A higher threshold value for spatial sharing may beused for the case where the received BSS color indicates a differentBSS.

Several spatial sharing example cases are identified herein. For thesimplicity of illustration, a node that attempts to spatially share thedirectional TXOP between the first transmitter and first receiver may bereferred to as a second transmitter herein. The potential spatialsharing case examples may be categorized according to whether the secondtransmitter can hear the first transmitter's omni- and directionaltransmissions and the first receiver's omni-transmissions. The followingprovide a description of example cases.

In an example case, which may be referred to as case 1, the secondtransmitter may be able to receive the omni-frame(s) (preceding thedirectional TXOP) transmitted by the first transmitter and firstreceiver, and the directional frame(s) within the TXOP. The receivedomni frames and/or directional frames indicate that the subsequent TXOP(and data frames with the TXOP) may be a directional transmission, andallow their directional TXOP to be spatially shared by other nodes. Thesecond transmitter may infer that this is case 1 by observing a firstomni-frame from the first transmitter and a second omni-frame from thefirst receiver, and then the omni-preamble of the subsequent directionalframe from the first transmitter, and by observing the subsequentdirectional transmission from the first transmitter.

In another example case, which may be referred to as case 2, the secondtransmitter may be able to receive the omni-frame(s) (preceding thedirectional TXOP) transmitted by the first transmitter and firstreceiver, but not the directional frame(s) within the TXOP. The receivedomni-frames indicate that the subsequent TXOP (and data frames with theTXOP) may be a directional transmission, and allow their directionalTXOP to be spatially shared by other nodes. The second transmitter mayinfer that this is case 2 by observing a first omni-frame from the firsttransmitter and a second omni-frame from the first receiver, and thenthe omni-preamble of the subsequent directional frame from the firsttransmitter, and by not observing the subsequent directionaltransmission from the first transmitter.

In a further example case, which may be referred to as case 3, thesecond transmitter may be able to receive the omni-frame(s) (precedingthe directional TXOP) transmitted by the first receiver and thedirectional frame(s) within the TXOP, but not the omni-frame (precedingthe directional TXOP) transmitted by first transmitter. The receivedomni-frame(s) and/or directional frame(s) indicates that the subsequentTXOP (and data frames with the TXOP) may be a directional transmission,and allow their directional TXOP to be spatially shared by other nodes.The second transmitter may infer that this is case 3 by not observing afirst omni-frame from the first transmitter, observing a secondomni-frame from the first receiver and the omni-preamble of thesubsequent directional frame from the first transmitter, and observingthe subsequent directional transmission from the first transmitter.

In an additional example case, which may be referred to as case 4, thesecond transmitter may be able to receive the omni-frame(s) (precedingthe directional TXOP) and the omni-preamble of the subsequentdirectional frame transmitted by the first transmitter, but not theomni-frame (preceding the directional TXOP) transmitted by the firstreceiver and the directional frame(s) within the TXOP. The received omniframe(s) and/or omni-preamble of the directional frame(s) indicates thatthe subsequent TXOP (and data frames with the TXOP) may be a directionaltransmission, and allow their directional TXOP to be spatially shared byother nodes. The second transmitter may infer that this is case 4 byobserving a first omni-frame and the omni-preamble of the subsequentdirectional frame from the first transmitter, by not observing thesubsequent directional transmission from the first transmitter, and bynot observing a second omni-frame from the first receiver. In otherwords, observing a gap of transmission between the first omni-frame andthe omni-preamble of the subsequent directional frame from the firsttransmitter.

In yet another example case, which may be referred to as case 5, thesecond transmitter may be able to receive the directional frame(s)within the TXOP, but not the omni-frames (preceding the directionalTXOP) transmitted by the first transmitter and first receiver. Thereceived directional frame(s) indicates that the subsequent TXOP (anddata frames with the TXOP) may be a directional transmission, and allowtheir directional TXOP to be spatially shared by other nodes. The secondtransmitter may infer that this is case 5 by not observing a first omniframe and the omni-preamble of the subsequent directional frame from thefirst transmitter, and a second omni frame from the first receiver, andby observing the subsequent directional transmission from the firsttransmitter. The identification of spatial sharing case may be used bythe second transmitter in the procedure of spatial sharing in furtherexamples described herein.

Several signaling examples and example procedures for spatial sharingare described herein. Examples of spatial sharing exchange mechanismsare described herein. In an example, a first transmitter and a firstreceiver may begin their TXOP of directional transmission: omni-framesexchange followed by directional transmission in the TXOP. Any secondtransmitter that wants to spatially share/reuse the directional TXOPbetween the first transmitter and first receiver may monitor the channeland decide whether the observed signals meet the criteria of one of thespatial sharing cases defined above. Upon identifying that this is apotential spatial sharing case, the second transmitter may transmit aspatial sharing request (for example, SS-Req) frame to a STA, ormultiple STAs. The STAs which receive the SS-Req frame from the secondtransmitter may reply with a spatial sharing response (for example,SS-Resp) frame indicating that receiver-side spatial sharing conditionsare met and communication between the second transmitter and receivermay begin. The names of spatial sharing request (for example, SS-Req)and spatial sharing response (for example, SS-Resp) frames may begeneric, and interchangeable with frames pairs such as RTS and CTS, orPoll and Poll-Response frames. In this example, methods and mechanismswhich enable the spatial sharing exchange between the second transmitterand receiver are described. The second transmitter may perform backoff acertain interframe space away upon the time it detects and determinesspatial sharing conditions are met for a potential spatial sharing case.

Examples of receiver spatial sharing conditions are described herein. Inan example, the STAs which successfully receive the SS-Req frame maycheck spatial sharing condition as a potential second receiver. Thereceiver-side spatial sharing conditions may be different depending onthe directional-transmission capability of the STA. If the potentialsecond receiver did not receive any omni or directional transmissionfrom the first transmitter and/or first receiver, then it may beconsidered that receiver-side spatial sharing condition foromni-direction reply is met. The potential second receiver may replywith an SS-Resp frame using an omni-transmission regardless of itscapability of directional transmitting or receiving. If the potentialsecond receiver received any omni or directional transmission from thefirst transmitter and/or first receiver but it does not have thecapability of directional transmitting or receiving, it will not replyany SS-Resp frame. If the potential second receiver received any omni ordirectional transmission from the first transmitter and/or firstreceiver and it has the capability of directional transmitting orreceiving, the STA may need to determine whether it is able to perform adirectional transmission on which it may null the direction of anyreceived signals from the first transmitter and/or first receiver and atthe same time make the transmission to the second transmittersuccessful. If so, the STA may reply with an SS-Resp frame in theappropriately chosen direction. Otherwise (where the spatial sharingcondition is not met for the potential second receiver), it may notreply with any SS-Resp frame.

Examples of spatial sharing exchange procedures are described herein.Further, examples of spatial sharing exchange with unicast transmissionsare described herein. In an example, the second transmitter may beginspatial sharing exchange with a STA in a unicast way. If the secondtransmitter does not receive any SS-Resp frame from the desired STA, orthe SS-Resp frame from the STA is not decodable, the second transmittermay wait a certain interframe space (for example, xIFS), and chooseanother STA again. The second transmitter may repeat the above mentionedprocedure until it successfully receives an SS-Resp frame from thedesired STA or the remaining TXOP duration of the first transmission maynot allow a spatial sharing transmission.

Table 1 provides an exemplary request frame, which may be referred to asan SS-Req frame. The spatial sharing request frame (for example, SS-Req)may be defined as in Table 1. One reserved Subtype value in the FrameControl field may be used to indicate the SS-Req frame type. Theduration field may be limited by the duration of the first transmissionof spatial sharing. For example, the duration field may be less than theremaining TXOP duration from the first transmission.

TABLE 1 Frame Duration RA TA FCS Control

In another example method, the second transmitter may carry moreinformation than a simple request. For example the second transmittermay include the spatial sharing case in the SS-Req, whether theimmediate ACK or delayed ACK is expected for the communications betweenthe second pair. It may request more information such as link adaptationinformation, channel state information (CSI), preferred direction ID,etc. In this case, the SS-Req frame may be designed as in Table 2. Table2 provides another exemplary request frame, which may be referred to asan SS-Req frame.

TABLE 2 Frame Duration RA TA SS-Req SS-Req FCS Control ControlInformation

An SS-Req Control field may carry some or all of the followinginformation: Spatial sharing case ID (which may or may not be anoptional field); ACK policy for the second transmission in spatialsharing case; and/or traffic identifier (TID) for the secondtransmission in spatial sharing case.

SS-Req Information field may carry some or all of the followinginformation. The field may carry an modulation and coding scheme (MCS)request. The second transmitter may use this to ask the receiver toreport the preferred MCS level. The field may also carry a transmitpower/link margin report request. The second transmitter may use this toask the receiver to reply with transmit power and link margin used forthe response frame. In addition, the field may carry a CSI request. Thesecond transmitter may use this to ask the receiver to feedback thechannel state information measured at receiver side. Further, the fieldmay carry a preferred sector/direction ID request. The secondtransmitter may use this to ask the receiver report the preferred sectoror direction ID.

In another example method, the SS-Req frame may utilize a field whichincludes all these information fields mentioned herein. One way may beto reuse the HT field defined in the current unmodified IEEE 802.11,which may include an HT variant and a VHT variant. Both variants may beused to convey link adaptation and CSI information. Or a new variant,such as a high efficiency WLAN (HEW) variant, may be defined to carrythis information.

In a further example method, a null data packet (NDP) SS-Req frame maybe utilized. The NDP SS-Req frame may contain a PHY header only and mayhave no MAC body included. The SIG field of the PHY header may includeNDP MAC frame type field, NDP MAC frame type may indicate this is an NDPSS-Req frame. Table 3 provides an exemplary request frame, which may bereferred to as an SS-Req frame and specifically as an NDP SS-Req frame.

TABLE 3 NDP MAC RA TA SS-Req SS-Req frame type Control Information

If the STA successfully receives the SS-Req frame, and the receiverspatial sharing condition has been met, the STA may reply with anSS-Resp frame.

In one method, the SS-Resp frame may be simply indicating that thepotential second receiver meets the spatial sharing condition, and readyfor the spatial sharing communication. Thus, the SS-Resp frame may usethe example design shown in Table 4. One reserved Subtype value in theFrame Control field may be used to indicate the SS-Resp frame. Theduration value may be the value obtained from the Duration field of theimmediately previous SS-Req frame, minus the time, in microseconds,required to transmit the SS-Resp frame and its short interframe space(SIFS) interval.

TABLE 4 Frame Duration RA TA FCS Control

In yet another example method, the second transmitter may request moreinformation in an SS-Req frame. The SS-Resp frame may includeinformation requested in the SS-Req frame, such as link adaptationinformation, CSI, preferred direction ID, etc. In this case, the SS-Respframe may be designed as shown in Table 5.

TABLE 5 Frame RA TA SS-Resp FCS Control Information

The SS-Resp Information field may carry some or all of the followinginformation. The field may carry a preferred MCS. The potential secondreceiver may use this field to report the preferred MCS level. The fieldmay also carry a transmit power/link margin. The potential secondreceiver may use this field to report transmit power and link marginused for the response frame. Further, the field may carry CSI. Thepotential second receiver may use this field to feedback the channelstate information measured at the receiver side. Different formats ofCSI feedback may be utilized herein. In addition, the filed may carry apreferred sector/direction ID. The potential second receiver may usethis field to report the preferred sector or direction ID.

In still another example method, the SS-Req frame may reuse the HT fielddefined in current unmodified IEEE 802.11, which includes HT variant andVHT variant. Both variants may be used to convey link adaptation and CSIinformation. Or a new variant, such as a HEW variant, may be defined tocarry this information. The SS-Resp frame may use the same format too.

In yet a further example method, an NDP SS-Resp frame may be utilized.The NDP SS-Resp frame may contain a PHY header only and no MAC framebodyincluded. The SIG field of the PHY header may be designed as shown inTable 6. An NDP MAC frame type may indicate this is an NDP SS-Req frame.An RA and a TA field may use a partial association identifier (AID) ofthe transmitter and receiver. The optional information field may containinformation such as MCS, CSI, transmit power control (TPC),section/direction ID, etc.

TABLE 6 NDP MAC RA TA Optional frame type Information

Examples of spatial sharing exchange with multicast transmissions aredescribed herein. The second transmitter may begin spatial sharingexchange in a multicast way. The second transmitter may transmit theSS-Req frame to a group of users. In order to signal a group of user,the second transmitter may use example methods, which may be referred toas methods 1 and 2, described herein.

An example method of using a group ID mechanism is described herein.This example method may be referred to as Method 1. The secondtransmitter may reuse the existing groups. For example, the uplink (UL)multi-user (MU)-MIMO group, or UL OFDMA group, etc. Or the AP may havedefined spatial sharing groups. The group ID may be carried in the SIGfield of the PHY header. The MAC frame format of non-NDP SS-Req framemay reuse the same frame format as in as is used with unicast as long asit has the group related fields in this PHY header. The NDP SS-Req framemay need to add group related fields, such as Group Type and Group IDfields in their PHY header. For example, NDP SS-Req frame may use thedesign shown in Table 7. Table 7 provides an exemplary NDP SS-Req framedesign with multicast transmissions.

TABLE 7 NDP MAC frame Color bit Group Group ID Optional SS- type TypeReq informationThe STAs within the group may reply with the SS-Resp frame using aposition array corresponding with the group ID. If a UL OFDMA group isutilized, the response frames from STAs may use the UL OFDMA format, andeach STA may check the position array, and transmit on its assignedsub-channel. If a UL MU-MIMO group is utilized, the STAs may transmitSS-Resp frame in an UL MU-MIMO format, and they may be separated inspatial domain. If the spatial sharing group is utilized, the STAs maytransmit SS-Resp frame with time/frequency/spatial domain separation.The MAC frame format of non-NDP SS-Resp frame may reuse the same frameformat as is used with unicast as long as it has the Group relatedfields in this PHY header. The NDP SS-Resp frame may need to add grouprelated fields, such as Group Type and Group ID fields in their PHYheader. For example, NDP SS-Resp may use the design shown in Table 8.The MAC frame format of non-NDP SS-Resp frame may reuse the same frameformat as is used with unicast as long as it has the Group relatedfields in this PHY header. The NDP SS-Resp frame may need to add grouprelated fields, such as Group Type and Group ID fields in their PHYheader. For example, NDP SS-Resp may use the design shown in Table 8.Table 8 provides an exemplary NDP SS-Resp frame design with multicasttransmissions.

TABLE 8 NDP MAC Color bit Group Type Group ID Optional frame typeSS-Resp information

An example method of using multiple AIDs or a broadcast frame totransmit an SS-Req frame is described herein. This example method may bereferred to as Method 2. In this method, the second transmitter may usemultiple AIDs of STAs of interest in the MAC header or the framebody tomulticast the SS-Req frame. Alternatively, the second transmitter mayset the RA field in the SS-Req frame to the Broadcast address tobroadcast the SS-Req frame. With this method being used, it is possiblethat multiple STAs may meet the spatial sharing condition, and intend totransmit SS-Resp frame to the second transmitter. The STAs may need toaccess the channel medium using a carrier sense multiple access withcollision avoidance (CSMA/CA) scheme.

FIG. 8 is a diagram of example procedures of a spatial sharing exchangewith multicast/broadcast transmission. As shown in procedure 800, asecond transmitter may transmit an SS-Req frame to multiple STAs 810.The multiple STAs may check if they meet the spatial sharing condition.The multiple STAs may then compete and the winner may gain the access tothe channel medium to transmit its SS-Resp frame 820. For example, eachSTA that receives the SS-Req may check if it meets the spatial sharingcondition. Each STA that meets the spatial sharing condition may competeto gain the access to the channel medium to transmit its SS-Resp frame.If collision happens 830, the SS exchange may fail, and the transmittermay check the TXOP duration and restart a new spatial sharing exchange.If collision does not happen 840, then the one winning STA maysuccessfully transmit the SS-Resp frame. Another STA or an AP mayaccordingly receive the SS-Resp frame from the winning STA. That winningSTA may become the second receiver and the spatial sharing may start840.

The STAs may perform spatial sharing exchange backoff. This backoff maybe independent from any other backoff functions. In order to raise thepriority of the SS exchange, the STAs may wait x interframe space(s)(xIFS) after confirming of SS condition, and begin the SS backoff.

In an alternative method, the second transmitter may reserve N severaltime slots for the SS-Resp. Each STA which meets the SS condition mayrandomly select a number k between 0 and N−1, and then transmit aSS-Resp frame on the k+1^(th) time slot. The STA which successfullytransmits SS-Resp in the earliest time slot may win the contention.Other rules to select the winning STA may apply.

In a third alternative method, instead of reserving N time slots, thetransmitter may define N sub-channel(s), and STAs may compete on thesub-channel in a similar way.

Upon identification of a potential spatial sharing case as describedherein, the second transmitter may choose a second receiver to spatiallyshare the TXOP between the first transmitter and first receiver, andmake sure its transmission to the second receiver may not interfere withthe TXOP between the first transmitter and first receiver. In exampledescribed herein, each STA may be an AP or a non-AP STA.

FIG. 9 is a diagram of an example of spatial sharing. As shown indiagram 900, in an example, which may be referred to as Spatial SharingCase 1, a second transmitter 930 (for example, a STA3) may receive anomni-transmission of a first transmitter 910 (for example, a STA1) andfirst receiver 920 (for example, a STA2), and a directional-transmissionfrom the first transmitter 910 to the first receiver 920.

In an example method, which may be referred to as Method 1, a secondtransmitter 930 may null the direction of the first receiver 920 in allits transmissions to a second receiver. A second transmitter will usethe spatial sharing exchange procedures described herein to choose asecond receiver. Considering an example as depicted in FIG. 9 for thepurpose of illustration, where each STA can be an AP or non-AP STA. STA1 (910) may be the first transmitter, STA 2 (920) may be the firstreceiver, and STA 3 (930) may be the second transmitter. Upon detectingthat this is spatial sharing case 1, STA 3 (930) may send a directionalSS-Req frame, which nulls the direction of STA2 (920). If a potentialsecond receiver STA does not have the capability of directionaltransmission and reception, then it may transmit only anomni-directional SS-Resp frame responding to the STA3's (930)directional SS-Req frame. In this case, such a STA may respond with aSS-Resp frame only if it did not hear any omni-directional ordirectional transmission from STA1 (910) and STA2 (920). For example,STA5 (950) may respond to STA3 (930) but STA4 (940) may not. If apotential second receiver STA has the capability of directionaltransmission and reception, then it may transmit a directional SS-Respframe responding to the STA3's (930) directional SS-Req frame if thereceiver-side spatial sharing conditions as described above are met.

After a successful spatial sharing exchange, an appropriate secondreceiver may be chosen for the purpose of spatial sharing of the TXOPbetween the first transmitter and first receiver. Then, the secondtransmitter may send a directional frame to the second receiver withoutinterfering with the directional transmission from the first transmitterto the first receiver. One example method to implement the directionaltransmission may be for the second transmitter to beamform to thedirection of the second receiver and also null in the direction of thefirst receiver at the same time.

The second transmitter may terminate its transmission to the secondreceiver before the directional frame from the first transmitter to thefirst receiver is finished (e.g., before the first receiver transmitsACK back to the first transmitter). The second receiver may be requiredto postpone its ACK frame corresponding to the data frame transmittedfrom the second transmitter until the TXOP between first transmitter andfirst receiver is finished. A Postponed Block ACK scheme may be used inthis case, for example.

In an example method, which may be referred to as Method 2, a secondtransmitter may null the direction of the first receiver, firsttransmitter and direction of the first transmitter's directionaltransmission/reception in all its transmissions to a second receiver. Asecond transmitter may use the spatial sharing exchange proceduresdescribed above to choose a second receiver. Considering an example asdepicted in FIG. 9 for the purpose of illustration, where each STA canbe an AP or non-AP STA, STA 1 (910) may be the first transmitter, STA 2(920) may be the first receiver, and STA 3 (9300 may be the secondtransmitter.

Upon detecting that this is spatial sharing case 1, STA 3 (930) may senda directional SS-Req frame, which may null the direction of STA1 (910),the direction of STA2 (920) and directional transmission(s) from STA1(910) to STA2 (920). If a potential second receiver STA does not havethe capability of directional transmission and reception, then it maytransmit only an omni-directional SS-Resp frame responding to STA3's(930) directional SS-Req frame. In this case, such a STA may respondwith a SS-Resp frame only if it did not hear any omni-direction anddirectional transmission from STA1 (910) and STA2 (920). For example,STA5 (950) may respond but STA4 (940) may not. If a potential secondreceiver STA has the capability of directional transmission andreception, then it may transmit a directional SS-Resp frame respondingto the STA3's (930) directional SS-Req frame if the receiver-sidespatial sharing conditions described herein are met.

After successful spatial sharing exchange, an appropriate secondreceiver may be chosen for the purpose of spatial sharing of the TXOPbetween the first transmitter and first receiver. Then, the secondtransmitter may send a directional frame to the second receiver withoutinterfering with the TXOP between the first transmitter and the firstreceiver. One example method to implement the directional transmissionmay be for the second transmitter to beamform to the direction of thesecond receiver and also null in the direction of the first transmitter,first receiver and direction of first transmitter's directionaltransmission and reception at the same time.

The second transmitter and second receiver may share the entire lengthof the rest of TXOP between the first transmitter and first receiver.The second receiver may transmit its ACK frame corresponding to the dataframe transmitted from the second transmitter using the same antennapattern as it sends the SS-Resp frame. The second transmitter mayreceive the ACK frame sent back from the second receiver using the sameantenna pattern in its data transmission to the second receiver.

FIG. 10 is a diagram of another example of spatial sharing. As shown indiagram 1000, in an example, which may be referred to as Spatial SharingCase 2, a second transmitter 1030 may receive an omni-Tx of a firsttransmitter 1010 and first receiver 1020, but not directional-Tx fromthe first transmitter 1010 to the first receiver 1020.

In an example method, which may be referred to as Method 1, a secondtransmitter 1030 may null the directional transmission/reception of thefirst receiver 1020 in all of its transmissions to a second receiver.This method may be the same as Method 1 for spatial sharing Case 1,except the second transmitter may identify this as Spatial Sharing Case2.

In an example method, which may be referred to as Method 2, a secondtransmitter 1030 may null the direction of the first receiver 1020 andthe direction of the first transmitter 1010 in all of its transmissionsto a second receiver. This method may be the same as Method 2 forSpatial Sharing Case 1, except the second transmitter may identify thisas Spatial Sharing Case 2 and its directional transmission may null thedirection of the first transmitter and first receiver.

In an example, a node 1050 may respond to the second transmitter's 1030directional SS-Req frame if it did not receive any omni-directional ordirectional transmission from the first transmitter 1010 and firstreceiver 1020. For example, node 1050 may respond to the secondtransmitter 1030 but node 1040 may not.

FIG. 11 is a diagram of an example of signaling in a spatial sharingscenario (SSS). As shown in scenario 1100, an AP1 1110 may start a frameexchange with an RTS 1130, which may be an omni-RTS, to solicit a CTSresponse 1140, which may be an omni-CTS, from a STA1 1120 and then usethe omni-transmission to set up protection for the duration of abeamformed data transmission 1150.

Further, an AP2 1170 may receive the omni-transmissions of AP1 1110and/or STA1 1120. For example, AP2 1170 may receive the frame exchangebetween AP1 1110 and STA1 1120. In this way, AP2 1170 may detect a SSSwith an overlapping BSS based on the received frame exchange. In anexample, AP may not receive the directional transmissions of AP1 1110and/or STA1 1120.

Also, AP2 1170 may transmit a directional poll request 1160, such as anSS-Req frame, to STAs associate with AP2 1170. AP2 1170 may thereby nulldirectional transmission associate with potentially interfering nodesbase on the detected SSS. For example, AP2 1170 may null directionaltransmissions associate with AP1 1110 and STA1 1120. AP2 1170 may thenreceive a poll response 1165, which may be an SS-Resp frame, from atleast one STA associated with AP2 1170. For example, AP2 1170 mayreceive the poll response 1165 from STA2 1180.

AP2 1170 may then transmit directional, beamformed data signals 1190 tothe at least one STA, which may be STA2 1180. As a result, AP2 1170 mayenable simultaneous beamformed transmission in the overlapping BSS.

FIG. 12 is a diagram of a further example of spatial sharing. As shownin diagram 1200, in an example, which may be referred to as SpatialSharing Case 3, a second transmitter 1230 may receive anomni-transmission of the first receiver 1220 and thedirectional-transmission from the first transmitter 1210 to the firstreceiver 1220, but not the omni-transmission of the first transmitter1210.

In an example method, which may be referred to as Method 1, a secondtransmitter 1230 may null the direction of the first receiver 1220 inall of its transmissions to a second receiver. This method may the sameas method 1 for Spatial Sharing Case 1, except the second transmittermay identify this as Spatial Sharing Case 3.

In an example method, which may be referred to as Method 2, a secondtransmitter 1230 may null the direction of the first receiver 1220 andthe direction of the first transmitter's 1210 directionaltransmission/reception. This method may be the same as method 2 forspatial sharing Case 1, except the second transmitter will identify thisas spatial sharing case 3 and its directional transmission will null thedirection of the first receiver and the direction of the directionaltransmission of node 1210.

In an example, a node 1250 may respond to the second transmitter's 1230directional SS-Req frame if it did not receive any omni-directional ordirectional transmission from the first transmitter 1210 and firstreceiver 1220. For example, node 1250 may respond to the secondtransmitter 1230 but node 1240 may not.

FIG. 13 is a diagram of an additional example of spatial sharing. Asshown in diagram 1300, in an example, which may be referred to asspatial sharing case 4, a second transmitter 1330 may receiveomni-transmission of the first transmitter 1310, but not theomni-transmission of the first receiver 1320 and thedirectional-transmission from the first transmitter 1310 to the firstreceiver 1320.

In an example method, which may be referred to as Method 1, a secondtransmitter 1330 may use an omni-direction transmission to a secondreceiver. The second transmitter 1330 may use the spatial sharingexchange procedures described herein to choose a second receiver.Consider an example as depicted in diagram 1300, for the purpose ofillustration, where each STA or node can be an AP or non-AP STA. STA11310 may be a first transmitter, STA2 1320 may be a first receiver, andSTA3 1330 may be a second transmitter. Upon detecting that this isspatial sharing scenario, which may be spatial sharing case 4, STA3 1330may send an omni poll frame. If a potential second receiver STA does nothave the capability of directional transmission and reception, then itmay transmit only an omni-directional SS-Resp frame responding to theSTA3's 1330 omni SS-Req frame. In this case, such a STA may respond witha SS-Resp frame only if it did not hear any omni-direction anddirectional transmission from STA1 1310 and STA2 1320. For example, STA51350 may respond to the second transmitter 1330 but STA4 1340 may not.If a potential second receiver STA has the capability of directionaltransmission and reception, then it can transmit directional SS-Respframe responding to the STA3's 1330 SS-Req frame if the receiver-sidespatial sharing conditions described herein are met.

In an example, after a successful spatial sharing exchange, anappropriate second receiver may be chosen for the purpose of spatialsharing of the TXOP between the first transmitter and first receiver.Then, the second transmitter may send an omni data frame to the secondreceiver without interfering with the directional transmission from thefirst transmitter to the first receiver. The second transmitter mayterminate its transmission to the second receiver before the directionalframe from the first transmitter to the first receiver is finished(e.g., before the first receiver transmits ACK back to the firsttransmitter). In an example, there may be two choices for the secondreceiver to transmit its ACK frame corresponding to the data frametransmitted from the second transmitter. In one choice, the secondreceiver may have to postpone its ACK frame corresponding to the dataframe transmitted from the second transmitter until the TXOP betweenfirst transmitter and first receiver is finished. A Postponed Block ACKscheme may be used. In another choice, in order to allow the secondreceiver to send back ACK frame with existing ACK timing, the secondtransmitter may choose the length of the data frame to the secondreceiver to be aligned with the duration of the directional data framefrom the first transmitter. In this way, both data frames from the firstand second transmitters may end at the same time, then the secondreceiver may transmit its ACK frame corresponding to the data frametransmitted from the second transmitter a SIFS time after the end of thedata frame from the first transmitter using the same antenna pattern asits response frame to the second transmitter in previous Spatial Sharingexchanges.

In an example method, which may be referred to as Method 2, a secondtransmitter 1330 may null the direction of the first transmitter 1310 inall of its transmission to a second receiver. A second transmitter 1330may use the spatial sharing exchange procedures described herein tochoose a second receiver. Consider an example as depicted in diagram1300, for the purpose of illustration, where each STA can be an AP ornon-AP STA. STA1 1310 may be the first transmitter, STA2 1320 may be afirst receiver, and STA3 1330 may be the second transmitter. Upondetecting that this is spatial sharing case 4, STA3 1330 may send adirectional poll frame, which may null the direction of STA1 1310. If apotential second receiver STA does not have the capability ofdirectional transmission and reception, then it can transmit only anomni-directional SS-Resp frame responding to the STA3's 1330 directionalSS-Req frame.

In this case, such a STA may respond with a SS-Resp frame only if it didnot hear any omni-direction and directional transmission from STA1 1310and STA2 1320. For example, STA5 1350 may respond but STA4 1340 may not.If a potential second receiver STA has the capability of directionaltransmission and reception, then it can transmit a directional SS-Respframe responding to the STA3's 1330 SS-Req frame if the receiver-sidespatial sharing conditions described herein are met.

After a successful spatial sharing exchange, an appropriate secondreceiver may be chosen for the purpose of spatial sharing of the TXOPbetween the first transmitter and first receiver. Then, the secondtransmitter may send a directional frame to the second receiver as longas it does not interfere with the first transmitter when it receives ACKfrom the first receiver. One example method to implement the directionaltransmission may be for the second transmitter to beamform to thedirection of the second receiver and also null the direction of thefirst transmitter. The second transmitter and second receiver may sharethe entire length of the rest of a TXOP between the first transmitterand receiver. The second receiver may transmit its ACK framecorresponding to the data frame transmitted from the second transmitterusing the same antenna pattern as it sends the SS-Resp frame. The secondtransmitter may receive the ACK frame sent back from the second receiverusing the same antenna pattern in its data transmission to the secondreceiver.

FIG. 14 is a diagram of yet another example of spatial sharing. As shownin diagram 1400, in an example, which may be referred to as spatialsharing case 5, a second transmitter 1430 may receive adirectional-transmission from a first transmitter 1410 to a firstreceiver 1420, but not the omni-transmission of the first 1410transmitter and the first receiver 1420.

In an example method, which may be referred to as Method 1, a secondtransmitter 1430 may use an omni-direction transmission to a secondreceiver. A second transmitter 1430 may use the spatial sharing exchangeprocedures described herein to choose a second receiver. Consider anexample, as depicted in diagram 1400 for the purpose of illustration,where each STA can be an AP or non-AP STA. STA1 1410 may be the firsttransmitter, STA2 1420 may be the first receiver, and STA3 1430 may bethe second transmitter. Upon detecting that this is spatial sharingscenario, which may be spatial sharing case 5, STA3 1430 may send anomni poll frame. If a potential second receiver STA does not have thecapability of directional transmission and reception, then it cantransmit only an omni-directional SS-Resp frame responding to the STA3's1430 omni SS-Req frame. In this case, such a STA can respond with aSS-Resp frame only if it did not hear any omni-directional anddirectional transmission from STA1 1410 and STA2 1420. For example, STA51450 may respond but STA4 1440 may not. If a potential second receiverSTA has the capability of directional transmission and reception, thenit can transmit a directional SS-Resp frame responding to the STA3's1430 SS-Req frame if the receiver-side spatial sharing conditionsdescribed herein are met.

After a successful spatial sharing exchange, an appropriate secondreceiver may be chosen for the purpose of spatial sharing of the TXOPbetween the first transmitter and first receiver. Then, the secondtransmitter may send an omni-data frame to the second receiver sincesuch a transmission may not reach the first transmitter and receiveranyway. The second transmitter may transmit its omni-direction dataframes to the second receiver up to the remaining length of the TXOPbetween the first transmitter and the first receiver after spatialsharing is established. In an example, there may be two choices for thesecond receiver to transmit its ACK frame corresponding to the dataframe transmitted from the second transmitter. In one choice, the secondreceiver may have to postpone its ACK frame corresponding to the dataframe transmitted from the second transmitter until the TXOP betweenfirst transmitter and first receiver is finished. A postponed Block ACKscheme can be used. In another choice, in order to allow the secondreceiver to send back an ACK frame with existing ACK timing, the secondtransmitter may choose the length of its data frame to the secondreceiver to end at the same time as with one of the directional dataframes in the TXOP between the first transmitter and the first receiver.In this way, when the second transmitter switches to receive ACK framefrom the second receiver, it may not be interfered by the directionaltransmission between the first transmitter and receiver. Then the secondreceiver may transmit its ACK frame corresponding to the data frametransmitted from the second transmitter a SIFS time after the end of thedata frame from the first transmitter using the same antenna pattern asits response frame to the second transmitter in previous Spatial Sharingexchanges.

In an example method, which may be referred to as Method 2, a secondtransmitter 1430 may null the direction of the first transmitter's 1410directional transmission and reception in all of its transmission to asecond receiver. This method may be the same as method 2 for spatialsharing Case 1 and 4, except the second transmitter 1430 may identifythis as spatial sharing case 5 and its directional transmission may nullonly the direction of the first transmitter's 1410 directionaltransmission.

Example procedures for medium access after the processing of preamblesmay be used to support correct functioning of MAC after the processingof a preamble when the STA may decide that it may ignore the remainderof the packet based wholly or partly on the information contained in thepreamble, in a first part of the packet, or in an earlier part of thepacket. For example, such a decision may be made in the case of spatialsharing when it is expected that a new transmission or reception at theSTA may not impact the ongoing transmission that is destined for anotherSTA. In another example, such a decision may be made when it isdetermined that the packet being received is an OBSS transmission andmay be ignored for higher medium access efficiency.

FIG. 15 is a diagram of an example of a method of continued back-off. Inexamples, the receiving procedures 1500 for the STA associated with thecontinued backoff as illustrated in FIG. 15 may have one or more of thefollowing steps. For example, a STA may compare the energy level in themedium and an energy detection threshold. The energy detection thresholdmay be a CCA threshold.

In an example, a frame 1510 may be transmitted and may contain apreamble or a first part 1512, a MAC header 1514 and a frame body 1516.A STA may receive a wireless signal. An energy level of the receivedsignal may exceed a CCA threshold. The STA may receive a wireless signalincluding the preamble or a first part 1512 of the packet 1510. In anexample, the STA may receive the preamble or a first part 1512 of thepacket 1510 via a beamformed signal. In another example, the STA mayreceive the preamble or a first part 1512 of the packet 1510 via anomni-directional signal. The STA may determine, using a carrier sensemultiple access (CSMA) protocol, to ignore the payload portion of thepacket based on information contained in the preamble or a first part1512. The STA may also adjust the CCA threshold to account for thepayload portion of the packet. In addition, the STA may conduct CSMAmedium access during the payload and/or remainder portion of the packetusing the adjusted CCA threshold. The STA may access a channel with anupdated energy detection level. For example, the STA may conduct CSMAmedium access on the channel with an updated energy detection level.

A frame 1510 may be transmitted and may contain a preamble or a firstpart 1512, a MAC header 1514 and a frame body 1516. Further, a STA maydetect energy on the medium and then the PMD layer may issue aPMD_RSSI.indication to indicate that increased energy has been detected.The PMD_RSSI.indication may provide the detailed measured RSSI valueRSSI_measured.

The PHY layer may then issue a PHY_CCA.indication(Status=busy), at whichpoint the MAC layer may set the MAC/CCA status to busy 1520. The PHYlayer may issue a PHY_RXSTART.indication(RXVECTOR) to the MAC layer withthe RXVECTOR containing the information obtained from the preamble 1510.

The MAC layer or any other function within the STA may determine, partlyor wholly based on the information contained in the preamble 1512 and/orRXVECTOR, that the remainder of the frame 1510, such as the MAC header1514 and frame body 1516, may be ignored. The MAC layer may make thedecision to ignore the remainder of the frame based on the parameters inthe preamble and/or RXVECTOR, such as PAID, Sector ID, Group ID, Color,etc. In this way, the STA may decide to drop the packet based oninformation in the preamble 1512.

Once it has been determined that the remainder for the frame 1510 may beignored, the MAC layer may issue a PHY_RXSTOP.request primitive to thePHY layer to request that the PHY layer stop with the reception of thecurrent packet. The PHY layer or the STA, when receiving thePHY_RXSTOP.request may stop the reception of the current frame 1510 andreturn to RX/IDLE state 1530. An addition may be added to the receivestate machine when the PHY_RXSTOP.request is received and the STA mayreturn to RX/IDLE state 1530. The PHY layer may respond with aPHY_RXSTOP.confirm to indicate that the PHY layer has stopped thereception of the current packet. Alternatively, a PHY-RXEND.indicationmay be used by the PHY layer to indicate to the MAC layer that it hasreceived the PHY-RXSTOP.request and has stopped the reception of thecurrent frame 1510.

The PHY layer or the STA may set its energy detection level and signaldetection level using the current energy or RSSI level of the receivedpreamble and some margin, such as Energy_Detection_Margin orSignal_Detection_Margin. For example, the updated Energy_Detection_Levelmay be equal to RSSI_current+Energy_Detection_Margin or equal toCCA_Level+Energy_Detection_Level; the updated Signal_Detection_Level maybe equal to RSSI_current+Signal_Detection_Margin or equal toCCA_Level+Signal_Detection_Level; the updated CCA_Level may be equal toRSSI_current+CCA_Level_Margin. In addition, all updated values describedabove may also include some scalar values or be a function of parametersdescribed above. The updated values may be valid for the duration of thepacket obtained from the preamble 1512.

The MAC Layer or the STA may resume normal medium access proceduresafter a certain period of time. For example, the MAC Layer may resumebackoff 1550 after some period of time; such a period of time may takeinto account propagation time, processing time that is needed for a STAto determine that the current packet should be ignored partially orwholly based on the information obtained from the preamble. Such aperiod of time may be a slot, a SIFS, a PIFS, a DIFS or any other periodof time.

The PHY_RXSTOP.request primitive issued by the MAC layer may contain oneor more parameters such as Energy_Detection_Level,Signal_Detection_Level, Duration, Energy_Detection_Change,Signal_Detection_Change, and RX_State. Further, the PHY Layer may updateits Energy_Detection_Level and the Signal_Detection_Level using therelevant parameters such as Energy_Detection_Level andSignal_Detection_Level from the PHY_RXSTOP.request. The PHY Layer mayupdate its Energy_Detection_Level and the Signal_Detection_Level usingthe relevant parameters such as Energy_Detection_Change andSignal_Detection_Change from the PHY_RXSTOP.request. For example, theupdated Energy_Detection_Level may be equal to currentEnergy_Detection_Level+Energy_Detection_Change; the updatedSignal_Detection_Level may be equal to currentSignal_Detection_Level+Signal_Detection_Margin. Also, the updatedEnergy_Detection_Level and Signal_Detection_Level may be valid for theduration of the packet obtained from the preamble or for a Duration thatis equal to the parameter Duration in the PHY_RXSTOP.request. Inaddition, the RX_State may specify the state to which the STA/PHY layershould go after receiving PHY_RXSTOP.request. Some possible values forRX_State may be, RX/IDLE, PowerSave. When the RX_State equals toRX/IDLE, the PHY layer should continue to sense the channel, possiblyusing a new CCA levels such as Energy_Detection_Level and/orSignal_Detection_Level. If the backoff process is suspended 1540, it maybe resumed 1550 after some pre-defined period, such as a SIFS, PIFS orDIFS or a slot, from some point of time, such as the end of thepreamble. If the RX_State equals to PowerSave, then the STA/PHY layermay go into power saving mode.

The determination of the RX_State for the STA and/or PHY layer maydepend on the technology used. In case of spatial sharing, if it can bedetermined that the ongoing packet and any pending transmission orreception to be initiated by the receiving STA does not impact eachother, then the RX_State may be set to RX/IDLE; any suspended backoff1540 may be resumed 1550 after some set period of time. If any pendingtransmission of packets that may be initiated by the receiving STA maybe in conflict of the current ongoing packet, the RX_State may be set toPowerSave to provide higher energy efficiency. In case of technologiesintended for increased medium access efficiency, in which OBSS packetsare ignored (such as adaptive CCA settings), the RX_State may be setRX/IDLE with increased CCA, and/or Energy Detection and/or SignalDetection levels.

In the following examples, the various primitives used by the MAC andthe PHY layers to ensure correct medium access procedures afterreceiving a preamble are described. In an example, a PHY-RXSTOP.requestprimitive may be used. The PHY-RXSTOP.request primitive may be a requestby the MAC layer to the local PHY entity to terminate the reception ofthe PLCP protocol data unit (PPDU) currently being received.

The following describes example semantics of the service primitive. Theprimitive may provide the following parameters.

PHY-RXSTOP.request(            Signal_Detection_Level,           Energy_Detection_Level,            Duration,           Signal_Detection_Change,            Energy_Detection_Change,           RX_State            )

The Signal_Detection_Level parameter may be an integer or a value thatthe PHY entity shall use as a threshold value of RSSI or RCPI or otherpower measurement used for signal detections. The Energy_Detection_Levelparameter may be an integer or a value that the PHY entity shall use asa threshold value of RSSI or RCPI or other power measurement used forenergy detection. The Duration parameter may be an interval specified inμs, ms, TU or other time units. The Duration parameter may provide thevalidity duration for the parameter changes specified in thePHY-RXSTOP.request primitive, such as Signal_Detection_Level,Energy_Detection_Level, Signal_Detection_Change,Energy_Detection_Change, or RX_State. The Duration value may be obtainedfrom the PLCP header of the PPDU currently being received.

The Signal_Detection_Change may be a signed or unsigned integer thatspecifies the change in threshold value of RSSI or RCPI or other powermeasurement used for signal detection. The Energy_Detection_Change maybe a signed or unsigned integer that specifies the change in thresholdvalue of RSSI or RCPI or other power measurement used for energydetection. The RX_State parameter may take the value RX/IDLE orPowerSaving.

This primitive may be issued or generated by the MAC Layer to the localPHY entity when the MAC Layer has determined that the frame currentlybeing received by the PHY entity should be terminated.

The effect of receipt of this primitive is that the PHY Layer mayterminate or end the reception of the PPDU that is currently beingreceived. If an RX_State parameter is included in the primitive, the PHYlayer may enter the RX_State such as RX/IDLE or PowerSaving as specifiedin the PHY-RXSTOP.request primitive. If Signal_Detection_Level and/orEnergy_Detection_Level parameters are included in the primitive, the PHYlayer may adapt the value of the Signal_Detection_Level andEnergy_Detection_Level as its threshold level for signal detectionand/or energy detection. If a Duration parameter is included in theprimitive, the changes in signal and energy detection levels may bereverted when the interval specified by the Duration expires. IfSignal_Detection_Change and/or Energy_Detection_Change parameters areincluded in the primitive, the PHY layer may update its threshold levelfor signal detection and/or energy detection usingSignal_Detection_Change and/or Energy_Detection_Change. If a Durationparameter is included in the primitive, the changes in signal and energydetection levels may be reverted when the interval specified by theDuration expires. The RX_State of the PHY layer may be RX/IDLE when theinterval specified by the Duration expires, if no additional validenergy detection, signal detection or valid preamble have taken place,or when the packet is transmitting or receiving.

In another example, a PHY-RXSTOP.confirm primitive may be used. ThePHY-RXSTOP.confirm primitive may be issued by the PHY layer to the localMAC entity to confirm the termination of the reception of the PPDU thatwas currently being received. This primitive may be issued by the PHYlayer in response to a PHY-RXSTOP.request primitive issued by the MACentity. This primitive may be issued by the PHY layer to the local MACentity to confirm the change in CCA level, Signal Detection thresholdlevels, Energy Detection threshold levels as requested by the MAC entityin a PHY-RXSTOP.request primitive.

The following describes example semantics of the service primitive. Theprimitive may provide the following parameters.

PHY-RXSTOP.confirm(            Status,           Signal_Detection_Level,            Energy_Detection_Level,           Duration,            Signal_Detection_Change,           Energy_Detection_Change,            RX_State            )

The Status parameter may have the following values: Success, Failed,Failed_Without_Reason. The Signal_Detection_Level parameter may be aninteger or a value that the PHY entity has adapted as a threshold valueof RSSI or RCPI or other power measurement used for signal detections.The Energy_Detection_Level parameter may be an integer or a value thatthe PHY entity has adapted as a threshold value of RSSI or RCPI or otherpower measurement used for energy detection. The Duration parameter maybe an interval specified in μs, ms, TU or other time units. The Durationparameter may provide the validity duration for the parameter changesthat the PHY layer has adapted, such as Signal_Detection_Level,Energy_Detection_Level, Signal_Detection_Change,Energy_Detection_Change, or RX_State. The Signal_Detection_Change may bea signed or unsigned integer that specifies the change in thresholdvalue of RSSI or RCPI or other power measurement that the PHY layer hasadapted for signal detection. The Energy_Detection_Change may be asigned or unsigned integer that specifies the change in threshold valueof RSSI or RCPI or other power measurement that the PHY layer adaptedfor energy detection. The RX_State parameter may take the value RX/IDLEor PowerSaving and indicate the current RX_State of the PHY Layer.

This primitive may be issued or generated by the PHY Layer to the localMAC entity when the PHY layer has completed one or more of the followingoperations: the PHY layer has terminated the reception of the PPDU thatwas being received; the PHY layer has transitioned into the RX_Statedesired, e.g., as specified by the PHY-RXSTOP.request primitive; and thePHY layer has adapted new or updated its signal and energy detectionthreshold levels. The effect of receipt of this primitive by the MACentity may be unspecified.

In another example, a PHY-RXEND.indication primitive may be used. Inaddition to the existing functionalities of PHY-RXEND.indication, thePHY-RXEND.indication primitive may be expanded to be issued by the PHYlayer to the local MAC entity to confirm the termination of thereception of the PPDU that was currently being received. This primitivemay be issued by the PHY layer in response to a PHY-RXSTOP.requestprimitive issued by the MAC entity. This primitive may be issued by thePHY layer to the local MAC entity to confirm the change in CCA level,Signal Detection threshold levels, Energy Detection threshold levels asrequested by the MAC entity in a PHY-RXSTOP.request primitive.

The following describes example semantics of the service primitive. Theprimitive may provide the following parameters.

PHY-RXEND.confirm(          RXERROR,          RXVECTOR,            Status,             Signal_Detection_Level,         Energy_Detection_Level,          Duration,         Signal_Detection_Change,          Energy_Detection_Change,         RX_State          )

The existing RXERROR parameter may have an additional value:Stopped_As_Requested to indicate the reception of the current PPDU hasbeen stopped per request by, e.g., the MAC layer. The existing RXVECTORmay remain unchanged. The Status parameter may have the followingvalues: Success, Failed, Failed_Without_Reason, Stopped_As_Requested.The Signal_Detection_Level parameter may be an integer or a value thatthe PHY entity has adapted as a threshold value of RSSI or RCPI or otherpower measurement used for signal detections. The Energy_Detection_Levelparameter may be an integer or a value that the PHY entity has adaptedas a threshold value of RSSI or RCPI or other power measurement used forenergy detections. The Duration parameter may be an interval specifiedin μs, ms, TU or other time units. The Duration parameter may providethe validity duration for the parameter changes that the PHY layer hasadapted, such as Signal_Detection_Level, Energy_Detection_Level,Signal_Detection_Change, Energy_Detection_Change, or RX_State. TheSignal_Detection_Change may be a signed or unsigned integer thatspecifies the change in threshold value of RSSI or RCPI or other powermeasurement that the PHY layer has adapted for signal detection. TheEnergy_Detection_Change may be a signed or unsigned integer thatspecifies the change in threshold value of RSSI or RCPI or other powermeasurement that the PHY layer adapted for energy detection. TheRX_State parameter may take the value RX/IDLE or PowerSaving andindicates the current RX_State of the PHY Layer.

In addition to the existing cases when the PHY-RXEND.indicationprimitive is generated, the PHY-RXEND.indication primitive may be issuedby the PHY Layer (e.g., in response to a PHY-RXSTOP.request primitiveissued by the MAC entity) to the local MAC entity when the PHY layer hascompleted one or more of the following operations: the PHY layer hasterminated the reception of the PPDU that was being received; the PHYlayer has transitioned into the RX_State desired, e.g., as specified bythe PHY-RXSTOP.request primitive; and the PHY layer has adapted new orupdated its signal and energy detection threshold levels.

In an example, the RSSI values above may be replaced by other powermeasurement values such as RCPI, or any other type of power measurement.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer-readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

1-26. (canceled)
 27. A method for use in a station (STA), the methodcomprising: receiving, by the STA, a wireless signal including apreamble of a packet, wherein a received energy level of the signalexceeds a clear channel assessment (CCA) threshold; and determining, bythe STA, using a carrier sense multiple access (CSMA) protocol, toignore a payload portion of the packet based on information contained inthe preamble.
 28. The method of claim 27, further comprising: adjusting,by the STA, the CCA threshold to account for the payload portion of thepacket; and conducting, by the STA, a CSMA medium access during thepayload portion of the packet using the adjusted CCA threshold.
 29. Themethod of claim 27, wherein the preamble of the packet is received bythe STA via a beamformed signal.
 30. The method of claim 27, wherein thepreamble of the packet is received by the STA via an omni-directionalsignal.
 31. The method of claim 27, wherein the determination to ignorethe payload portion is based on an RXVECTOR.
 32. The method of claim 27,further comprising: issuing, by the STA, a primitive to stop receptionof the packet.
 33. The method of claim 32, wherein the primitive is aPHY_RXSTOP.request primitive.
 34. A station (STA) comprising: aprocessor and a transceiver configured to receive a wireless signalincluding a preamble of a packet, wherein an energy level of the signalexceeds a clear channel assessment (CCA) threshold; and the processorand transceiver further configured to determine, using a carrier sensemultiple access (CSMA) protocol, to ignore a payload portion of thepacket based on information contained in the preamble.
 35. The STA ofclaim 34, further comprising: the processor further configured to adjustthe CCA threshold to account for the payload portion of the packet; andthe processor and transceiver further configured to conduct a CSMAmedium access during the payload portion of the packet using theadjusted CCA threshold.
 36. The STA of claim 34, wherein the preamble ofthe packet is received by the processor and transceiver via a beamformedsignal.
 37. The STA of claim 34, wherein the preamble of the packet isreceived by the processor and transceiver via an omni-directionalsignal.
 38. The STA of claim 34, wherein the determination to ignore thepayload portion is based on an RXVECTOR.
 39. The STA of claim 34,further comprising: the processor and transceiver further configured toissue a primitive to stop reception of the packet.
 40. The STA of claim39, wherein the primitive is a PHY_RXSTOP.request primitive.
 41. A firstnode comprising: a processor and a transceiver configured to receive oneor more frames exchanged between a second node and a third node, whereinthe second node is associate with the third node; the processor andtransceiver further configured to detect a spatial sharing scenario(SSS) with an overlapping basic service set (OBSS) based on the receivedone or more frames; the processor and transceiver further configured totransmit a directional poll request to at least a fourth node associatedwith the first node based on the detected SSS, wherein transmitting thedirectional poll request nulls directional transmissions associated withthe second node, the third node or both, and wherein the directionalpoll request is a spatial sharing request (SS-Req); the processor andtransceiver further configured to receive a direction poll response fromthe fourth node, wherein the directional poll response is a spatialsharing response (SS-Resp); and the processor and transceiver furtherconfigured to transmit one or more directional, beamformed transmissionsto the fourth node simultaneously with directional, beamformedtransmissions by the second node to the third node.
 42. The first nodeof claim 41, further comprising: the processor and transceiver furtherconfigured to receive omni-transmissions of the second node,omni-transmissions of the third node and directional transmissions ofthe second node to the third node.
 43. The first node of claim 41,further comprising: the processor and transceiver further configured toreceive omni-transmissions of the second node, omni-transmissions of thethird node and no directional transmissions of the second node to thethird node.
 44. The first node of claim 41, further comprising: theprocessor and transceiver further configured to receiveomni-transmissions of the third node, directional transmissions of thesecond node to the third node and no omni-transmissions of the secondnode.
 45. The first node of claim 41, further comprising: the processorand transceiver further configured to receive omni-transmissions of thesecond node, no omni-transmissions of the third node and no directionaltransmissions of the second node to the third node.
 46. The first nodeof claim 41, further comprising: the processor and transceiver furtherconfigured to receive directional transmissions of the second node tothe third node, no omni-transmissions of the second node and noomni-transmissions of the third node.